Aerial torpedo

ABSTRACT

587,438. Automatic steering control systems. BENDIX AVIATION CORPORATION. June 4, 1942, No. 7647. Convention date, May 15, 1941. [Class 38 (iv)] [Also in Group XXXVIII] A device for ascertaining the direction of a source of sound comprises directional and non-directional microphones, and means energized by the microphones to turn the support of the device in that direction. The device may be used to steer a projectile towards a source of sound such as an aeroplane.. In the arrangement shown a directional microphone 10, which may be of the ribbon type, is carried by a vertical shaft 20 that rotates a pointer 31 over a scale 32 and is also geared to a shaft 23. A non-directional microphone 27 is mounted above and close to the microphone 10. The output of the microphone 10 is connected through an amplifier 15 to windings on two opposite poles 18 of an indication motor 17, and the microphone 27 is similarly connected to poles 19 which are at right angles to the poles 18. The rotor 26 of this motor is geared to the shaft 23 and is thus able to rotate the microphone 10 about its vertical axis. The difference in the outputs from the microphones causes the microphone 10 to be turned by the shaft 23 until it faces the direction of the sound, which also will be indicated by the pointer 31. The same result can be obtained by using three stationary directional microphones instead of the single movable directional microphone 10. The three microphones are arranged one above the other and closely adjacent, the ribbon of each being displaced 120 degrees with respect&#39; to the others. The microphones are separately connected to three pole-windings of an indication motor the rotor of which having a winding that is connected to opposite polewindings of another motor, similar to the motor 17. The other windings of this motor are connected to a non-directional microphone. The rotors of the two motors are geared to one another and to an indicating pointer. In each case, the arrangement may be mounted on an aircraft to give the pilot some indication of the position of an enemy aircraft. A similar arrangement may be used for steering a selfsteering glider-projectile which, when dropped from an aeroplane in the path of approaching enemy aircraft, glides downwards and is steered towards the enemy aircraft by the noise of the engine. The glider-projectile may be provided with a suitable relay which explodes it when the noise of the target aircraft reaches a predetermined volume. Means may be provided also for exploding the projectile before it reaches the ground should it miss its target.

Feb. 28, 1950 A. A. STUART, JR

AERIAL TORPEDO Original Filed May 15, 1941 2 Sheets Sheet 1 v TAMP INVENTOR. Alfred A. Sl'aarfi J1 BY 6;

' ORNEY Feb. 28, 1950- A. A. STUART, JR 2,498,772

AERIAL TORPEDO Original Filed May 15, 1941 2 Sheets-Sheet 2 m Q 5 gm .NVENTOR.

fiyred A. Shari, v.5.

A ORNEY Patented Feb. 28, 1950 scam 'ronrano Alfred A. Stuart, Jr., Hasbrouck Heights, N. 1.,

assisnor to Bendix Aviation Corporation.

- Bendix, N. J., a corporation of Delaware Original application May 15, 1941, Serial No. 393,685, new Patent No. 2,422,448, dated June Divided and this application December 13, 1941, Serial No. 422,910

flclaims.

This invention relates to aerial torpedo devices which are adapted to be automatically guided or directed toward, or in the direction of, a sound source, and is a division of copending application Serial No. 393,685, filed May 15, 1941, now Patent No. 2,422,446, dated June 17, 1947.

An object of the present invention is to provide a novel automatic target-seeking dirigible bomb controlled by mechanism responsive to sound.

Another object of the invention is to provide novel means for automatically directing an object toward a desired source of sound.

A further object of the invention is to provide an automatic glider type device equipped with novel sound responding apparatus for directing or steering the glider in the direction of a desired source of sound.

Another object of the invention is to provide a novel glider device having control surfaces thereon with a novel sonic responsive apparatus, the energy output of which it utilized to control the glider surfaces thereby automatically directing the glider to a source of sound.

A still further object is to provide a novel target seeking dirigible bomb in the form of a glider having rudder and elevator control surfaces with a novel sonic responsive apparatus comprising a pair of directional microphones and a non-directional microphone, whereby the rudder and elevator surfaces are controlled in response to the energy output of the microphones so that the target seeking dirigible bomb is automatically directed toward a desired target which may constitute a source of sound such as that defined by the propeller or engine of an enemy bomber while in flight.

The above and other objects and novel features of the invention will more fully appear from the detailed description which follows when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purposes of illustration only and are not intended as a definition of the limits of the invention, reference for the latter purpose being had primarily to the appended claims. 7

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a schematic representation of one form of the novel arrangement of the microphones in accordance with the present invention,

Fig. 2 is a schematic representation of a second form of the present invention, embodying the use of a plurality of directional microphones and a 2 non-directional microphone in combination with indicating means for indicating the direction of a source of sound,

Fig. 3 is a graphic representation or pattern illustrating the output characteristics of the directional microphone when it is rotated 360 in azimuth, and

Fig. 4 is a diagrammatic and partially schematic representation of a novel target seeking dirigible bomb equipped with the novel means of the present invention.

The present invention contemplates the use of sonic responsive devices the voltage output of which is dependent upon the angular displacement of the devices with respect to a source of sound, and which is utilized to either operate an indicator to thereby indicate the direction of a sound source, or which may be converted into driving power for automatically driving or steering a projectile having control surfaces thereon to the source of sound. The sonic responsive devices may comprise either a rotatably mounted directional microphone together with a non-directional microphone, the output voltage of both of the microphones being amplified to energize an induction motor, whereby the latter operates to rotate the directional microphone to its null position, or a plurality of directional microphones together with a non-directional microphone so arranged with respect to a sound source that the output voltage of the microphones due to the sound waves intercepted thereby is communicated in amplified from to operate indicating means which indicate the direction of the source from which the sound waves emanate.

In both of the above-mentioned forms the ultimate output voltage of the microphone arrangement isutilized to operate indicating means for continuously indicating the direction of the source of sound. However, an equally important application of the above principle is contemplated in that the output of the microphones may be ultimately ultilized to'automatically direct a device having control surfaces thereontoward the source of sound. The device having the control surfaces thereon and adapted to be automatically controlled by the ultimate microphone output ma be another airplane, glider, target seeking dirigible bomb, etc.

A particular and desirable use of the abovedescribed automatic apparatus is for purposes of warfare. For example, in defensive warfare, a bomb built in the form of a glider having both elevator and rudder surfaces may be carried by an aircraft flying at an altitude higher than the enemy craft. A refined feature of this particular use may lie in the provision of a detonator which in respons to automatic volume control may be energized to detonate the bomb within any desired distance from the enemy target. It is to be noted that the glider device is not provided with any motivating power of its own and thus will tend to fall toward the earth only and will deviate from this path in response to the sound waves emanating from the enemy target at an altitude lower than the altitude of the-craft from which the bomb was dropped and in a position away from the plane dropping it. This feature avoids the possibility of the bomb following the 'plane which has discharged it, for the reason that the latter plane is at a greateraltitude' and the glider bomb itself cannot reverse its direction so as to fly upwardly.

Referring now to the drawings for a more detailed description of the present invention, and more particularlyto Fig. 1 thereof, there is illustrated a directional microphone l which may be of the ribbonor velocity type. Microphone I0, in the present instance, is shown as a ribbon type microphone having a magnet i I between the poles of which is supported a ribbon H by means of suitable means such as Bakelite I3. The ribbon i2 is connected by way of leads M to a suitabl and conventional vacuum tube amplifier i5,

the output of which is, in turn, connected by way of leads it to one phase of a two-phase induction motor ll whose stator poles 18 comprise the one phase while stator poles l9 comprise the second phase.

If it be desired to mount the structure of Fig. 1

upon an aircraft so as to at all times inform the pilot of the directionof a source of sound in which he is interested, the directional microphone III will be mounted upon a suitable shaft 20 which in turn has splined thereto a gear 26 type, having its output connected by way of a suitable flexible cable 28 to the input of a conventional and suitable vacuum tube amplifier 28 whose output in turn is connected by way of leads 30 to the second phase l9, IQ of the two-phase induction motor II.

By virtue of the 'fact that directional microphone 10 is a ribbon or velocity type microphone and the non-directional microphone 21 is of the vcrystal type, for example, the outputs of both microphones due to their inherent operating characteristics, are substantially 90 out of phase and since both amplifiers. l5 and 29 are of a similar type, the two inputs to the induction motor IHn'phases l8, l3 and I9, I9 are 90 apart which provides the desired condition for maximum torque of the induction motor l1.

Fora better understanding of the output characteristics of the directional microphone l0, reference is now made to Fig. 3 of the drawings wherein the form of the microphone output is shown in its' relation to the angular position of the microphone with respect to the sound source. The voltage output of the microphone throughout a rotation of 180 takes the form of a circle A while at areversal and a rotation of 180 by the microphone and its ribbon l2 in an opposite direction the voltage output takes the form of a second circle B, the two taken together forming a familiar figure eight pattern. It may be noted further-that 180 ambiguity in indication will be prevented for the reason that for each 180 rotation of the directional microphone a phase reage in .Jeads ll from the microphone.

versal of 180 ensues in the output so that the rotation of the induction motor is reversed for each 180.

When the plane of the ribbon 12 of the direc-- tional microphone I0 is parallel to thedirection of the sound source. the sound waves act equally on both sides of the ribbon [2 so that the latter does not vibrate and thus there is no output volt- Even though the output voltage of non-directional microphone 21 is uniform so that at all times phase l9, IQ of motor I! is energized, phas l8, I3 is de-energized and rotor 26 will not move.

As soon, however. as microphone I0 is displaced angularly with respect to the sound source, the plane of ribbon I2 is no longer parallel to the sound waves emanating from the source but is at some angular relationship with respect thereto and thus the ribbon is caused to vibrate and in proportion to the amount of its vibration a voltage is induced in leads l4, and amplified in the vacuum tube amplifier I5 to energize phase It, I8 of the induction motor whereby the rotor is now caused to turn, driving gear 25 which in turn drives gears 22 and 24 mounted on shaft 23 to angularly move gear 2| and shaft 20 therewith until microphone I0 is moved angularly to a position wherein its ribbon I2 is again placed in a relationship parallel to the sound waves emanating from the source. At this point the output of microphone I 0 is zero since it is in its null position and phase l8, I8 is de-energized, stopping rotation of rotor 26 and thus maintaining microphone l0 in its null position. Shaft 20 may be provided with a suitable pointer 3| to cooperate with-a stationary dial 32 carried by the craft so that at all times pointer 3| will indicate the direction oi the sound source.

The same result as obtained with the use of the structure of Fig. 1 for indicating the source of sound may be obtained by a slightly modified form of apparatus and comprises, as shown in Fig. 2, three directional microphones 33, 34 and 35, each of which is similar to the ribbon type directional microphone III of Fig. 1. These microphones 33, 34 and 35 are arranged or mounted one above the other,.closely adjacent each other, in a cluster and in such a manner that the ribbon of each is displaced with respect to the other. In this arrangement the microphones are stationary on the craft and their output constitutes three different voltages, each depending upon the angular relation of its respective ribbon with the sound source, and these outputs are in turn communicated by way of cables 33, 31 and 38 to each of three phases 39, 40 and ll of a three-phase Autosyn motor generally designated at 42.

With a change in the heading of the craft carrying the novel apparatus of Fig. 2, the output of each of the three microphones 33, 34 and 35 varies in accordance with the angular displacement of the respective microphones with respect to the sound source and this change in voltage in being communicated to the three phases of the Autosyn 42 produces or sets up a magnetic field whoseresultant changes thereby inducing a voltage in a coil 43 carried by a rotor 44 of the-Autosyn 42. The voltage thus induced in coil 43 is amplified in a vacuum tube amplifier 45 to energize phase 46 of a two-phase induction motor 41 which in all respects is similar to the induction motor l1 of Arranged either above or below the cluster of microphones 33, 34 and 35 and in close proximity thereto, is a non-directional microphone 48, similarto non-directional microphone 21 of Fig.

and ruddercontrol' surfaces 88 and 8| Mounted in the nose of the glider are two directional microphones 62. and 83 arranged one .above the other and displaced'angularly with respect to each other so that their ribbons are substansound waves emanating from a source of sound 1, whose uniform output is communicated by way of cable 49 to the input of a suitable vacuum tube amplifier 58, similar to amplifier 45, the output of-which constantly energizes the second phase 5| of the induction motor 41.

7 Induction motor 41, upon properenergization of both of its phases, drives its rotor 52 which is coupled by suitable means to driving gear 53, meshing with a gear 54. The latter gear is carried by a suitable shaft 55 which at one end is connected with the rotor 44 of Autosyn 42 and at its other end carries a pointer 56 cooperating with a stationary scale 51.

If it be assumed that the craft upon which the novel apparatus of Fig. 2 is mounted is in such a position that the outputs of the microphones 33, 34 and 35 are of a value whereby the rotor 44 of Autosyn 42 is maintained in a position shown in Fig. 2 and subsequently the craft changes its heading with respect to the sound source, the relationship of the microphones changes with respect to the source and this change produces three difierent voltages in cables 36, 31 and 38, whose ratios depend upon the amount of angular displacement from the direction of the sound source,

driving gear 54 by way of gear 53 to angularly move rotor 44 to a new position in which the voltage within coil 43 is reduced to zero. This is 'the null position for the rotor 44 and phase 46 of the induction motor is de-energized and at the same time that rotor 44 of the Autosyn 42 has been turned to its null position pointer 56 has been moved relatively with respect to dial or scale 51 to thus indicate the direction of the source of sound.

It will now be apparent to those skilled in the art that the apparatus of Fig. 2 is adapted for continuously indicating the sound source and difiers from the structure of Fig. l in that in the latter, microphone I0 is always urged bodily in the direction of the sound source whereas in the structure of Fig. 2 the microphones are all mounted stationarily with respect to the craft.

The above-described apparatus together with its principle of operation is adapted for many uses, one of which is of great importance in that it may be applied to a self-directed sound seeking glider type missile for use against nightflying enemy aircraft. This latter use is diagrammatically illustrated in Fig. 4 wherein is shown a glider 56 having wings 58 and elevator is 90 out of phase with the outputs of microphones 62 and 63 and is fed into the input of a suitable amplifier 51, similar in all respects to amplifiers. 64 and 65 of the directional microphones.

The elevator control surfaces 38 are Joined by a common shaft 68 having mounted thereon a gear sector 69 which meshes. with a worm 16 driven by the shaft 1| of an induction motor 12. This induction motor is a two-phase induction motor similar in all respects to those illustrated in both Figures 1 and 2.

The rudder surface BI is mounted for movement with a suitable shaft 13 carrying a gear sector 14 meshing with a gear 15 driven by shaft 16 of a second induction motor 11 constituting a two-phase induction motor of the same type as motor 12.

One phase ofeach of the induction motors 12 and 11 is energized by way of leads 18 from the amplifier 61 of the non-directional microphone output. The second phase of induction motor 12 is connected by way of lead 18 with the amplifier 65 of the output of the directional microphone 62 which may be termed in this instance the elevator control microphone, while the second phase of the induction motor 11 is connected by way of lead with the output of amplifier 54 connected to the output of the directional microphone 63 which may be termed the rudder control microphone. Each of the amplifiers 64, 65 and 61 may be connected with a, suitable source of power 8|.

For a better understanding of the operation of the novel device of Figure 4, let it be assumed that a defensive plane is flying over an enemy bomber which may be invisible due to either fog or night flying. The defensive plane discharges glider 58 and the latter will begin to glide and descend while the defensive plane may go into a slight climb to avoid energizing the controls at the nose of the glider. Since the glider has no motive power of its own, it is incapable of climbing and will thus tend to glide, or under the efiect of gravity be pulled earthwardly. Initially, the accuracy of the glider is low, but as it travels downwardly the volume of the sound waves from the source increases and the directive accuracy of the glider increases for the reason that microphones 62, 63 and 66 at the nose of the glider become energized, in the manner hereinabove set forth in connection with Figures 1 and 2, so that in accordance with the angular relation of the directional microphones 52 and 63 with respect to the source of sound, the second phases of the induction motors 12 and 11 will become energized so as to operate both rudder and elevator surfaces 60 and 6| to change the direction of 'fiight of the glider 58 until the latter is flying toward its target or the source of sound. Even if the target changes its heading, the glider will nevertheless follow it for the reason that the change in heading changes the sound source thus changing the outputs of directional microphones 62 and .83 which in turn causes a variation in the operation of induction motors I2 and 11 to again operate the rudder and elevator surfaces to direct the glider after the target.

From the foregoing it will now .be,apparent to those skilled in the art that a novel automatic sound directed device has been provided which may be termed a target seeking dirigible bomb of the sonic type which is particularly adapted for use against night-flying enemy aircraft. The projectile may be further provided with a suitable relay 82 which is connected to the output of amplifier 61 of the nondirectional microphone 66 and may constitute a marginal relay which will only respond to a predetermined amount of volume in amplifier 81 which may be provided with a suitable well-known automatic volume control device. This feature is useful in that the target'seeking dirigible bomb need not actually strike or hit its target but may be detonated due to the energization of relay '2 when the target seeking bomb is within a predetermined distance of the target which distance is determined by the volume of the sound waves emanating from the sound source.

In order to protect the ground crewshould the target seeking dirigible bomb fail to reach its target or a predetermined distance of its target, the glider may be provided with some well-known altitude control means whereby upon reaching a predetermined height above the earth the bomb may be discharged, thereby protecting the ground forces.

-There is thus provided a novel apparatus,

adapted to either indicate the source of sound waves or to control and automatically direct a device such as a target seeking dirigible bomb toward the sound source which consists in the conversion of sound waves into electrical power which may or may not be amplified so as to drive indicating or control means as a function of the direction of the sound source.

Although three embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. For example, various types of directional microphones besides the ribbon type microphone hereinabove described may be used and the non-directional microphone may be other than the crystal type discussed. The direct onal microphones together with the nondirectional microphone must be arranged one abovethe .otherand in close proximity to each other so that the sound waves intercepted by each are of a like phase so as to assure proper operation of the indicating or control means. Various changes may also be made in the design and arrangement of the parts without depart- Y in from the spirit and scope of the invention as the same will now be understood :by those skilled in the art. For a definition of the limits of the invention reference, will be had primarily to the appended claims.

What is claimed is:

1. An automatic sound directed device having a pair of control surfaces thereon, a pair of directional microphones arranged on .said device for intercepting and converting sound waves emanating from a source into electrical output energy, non-directional sound responsive means providing a continuous energy output independent of its position relative to the sound waves emanating from said source, and a pair of actuating devices for operating said control surfaces, whereby said device is directed toward said sound source, one of said actuating devices being energized by the output of one of said directional microphones and said non-directional .means and the other of said actuating devices being energized by the output of the other of non-directional microphone, and one of said 411- rectional microphones, and other driving means for said-rudder energized by the outputs of said non-directional microphone and the other of said directional microphones, whereby said device is directed toward said sound source.

3. An automatic sound directed device having an elevator and rudder thereon, a. pair of directional microphones arranged on said devicefor intercepting and converting sound waves emanating from a source into electrical output energy the value of which depends upon the angular displacement of said microphones relative to said source, a non-directional microphone providing a continuous energy output independent of its position relative to the sound waves emanating from said source, an induction motor for operating said elevator energized by the outputs of said non-directional microphone and one of said directional microphones, and a second induction motor for operating'said rudder energized by the outputs of said non-directional microphone and the other of said directional microphones, whereby said device is directed toward saidsound source.

4. An automatic sound directed-device having elevator and rudder control means thereon, a two-phase induction motor for operating said elevator control means, a two-phase induction motor for operating said rudder control means,

a directional microphone on said device for intercepting and converting sound waves emanating from a source of sound into electrical output energy the value of which is a function of the angular displacement of said microphone relative to said source, means connecting the output of said microphone with one phase of said elevator control motor, a second directional microphone mounted adjacent the first microphone for intercepting and converting sound waves emanating from said source into electrical output energy the value of which is a function of the angular displacement of the second microphone relative to said source, means connecting the output of said last-named microphone with one phase of said rudder control motor, and a non-directional microphone responsive to said sound waves for energizing the other phase of each of said induction motors whereby said elevator and rudder control means are operated to direct said device to said sound source.

5. An automatic sound directed device having elevator and rudder control means thereon, a. pair of directional microphones mounted on said proje'ctile for intercepting and converting sound waves emanating from a source into electrical output energy, the value of the output of each of said microphones being a function of the relative angular displacement of said device with respect to said sound source, a non-directional microphone providing a continuous energy output independent of its position relative to the sound waves emanating from said source, a polyphase induction motor the phases of which are energized by the outputs of said non-directional microphone and one of said directional microphones for operating said elevator control means when said one directional microphone moves from a predetermined relation with respect to said sound source to re-establish said relation, and a second polyphase induction motor the phases of which are energized by the outputs of said non-directional microphone and the other of said directional microphones for operating said rudder control means when said other directional microphone moves from a predetermined relation with respect to said sound source to re-establish said relation.

6. A target seeking dirigible bomb having elevator and rudder control means therefor, a pair of directional microphones mounted on said bomb for intercepting and converting sound waves emanating from a desired target source into electrical output energy, the value of the output of each of said microphones being a function of the relative angular displacement of said bomb with said target source, a non-directional microphone providing a continuous energy output independent of its position relative to the sound waves emanating from said source, driving means actuated by the outputs of said non-directional microphone and one of said directional microphones for operating said elevator control means when said one directional microphone moves from a predetermined relation with respect to said target source to thereby re-establish said relation, and driving means actuated by the outputs of said non-directional microphone and the other of said directional microphones for operating said rudder control means when said other directional microphone moves from a predetermined relation with respect to said target source to reestablish said last-named relation whereby said bomb is directed to said target source.

ALFRED A. STUART, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,137,222 Leon Apr. 27,1915 1,303,105 Murdock May 6, 1919 1,312,510 Baker Aug. 12, 1919 05 I 1,344,352 Parmele et a1. June 22, 1920 1,506,552 Angus Aug. 26, 1924 1,842,345 Eaton Jan. 19, 1932 1,991,443 Becker Feb. 19, 1935 2,062,275 Blumlein Nov. 24, @1936 30 2,109,475 Fanning Mar. 1, 1938 2,173,219 Anderson Sept. 19, 1939 2,282,030 Busignies May 5, 1942 FOREIGN PATENTS 35 Number Country Date 297,977 Germany Jan. 19, 1920 344,967 Great Britain Mar. 19, 1931 

